• KSBB Journal
• /
• v.14 no.3
• /
• pp.351-357
• /
• 1999

A marine bacterium Bacillus cereus ASK202, agarase producing strain, was treated with some mutagenic agents, ultraviolte(UV), 1-methyl-3-nitro-1-nitrosoguanidine(NTG), and ethyl methane sulfonate(EMS), several times for the increasing of the agarase production After mutagen treatment, we isolated one mutant strain treated with NTG showed the highest stability and agarase productivity and named as Bacillus cereus ASK202-N3. This Bacillus cereus ASK202-N3 strain was well grown in the modified marine medium containing 0.5%(w/v) agar, 0.3%(w/v) yeast extract, and 5.0%(w/v) NaCl, and the optimal initial pH, temperature and culture time were 7.8, $25^{\circ}C$ and 32h, respectively. In the optimal culture conditions, the agarase production was increased to 5.3 fold(850units/L) compared to that of the wild type.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.45 no.11
• /
• pp.44-49
• /
• 2008

We have proposed a clock recovery circuit for 13.56MHz RFID Tags using 100%, ASK RF input signal. The proposed clock recovery circuit generates clock pulses without reference clock by adapting register controlled DLL. The proposed circuit have designed by using a TSMC 0.18um 1P6M CMOS technology. The simulated results show that the phase locking time of the proposed circuit is about 6.4 usec and power consumption is about 43uW at supply voltage of 3.3V.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.17 no.3
• /
• pp.268-276
• /
• 1992

In this paper, we present an discrimination method of unknown digital modulated signals in noisy communication environment. We propose the use of an identification procedure based on time domain signal parameters. First, We extract instantaneous envelope. Frequency and difference phase as the basic feature informations from received signals. In order to identify signals using the extracted feature informations, we design the two dimensional feature space. The extracted feature infomations are mapped into2Dfeature space using 2D feature points. The procedure has been tested by simulations on a computer in noisy communication environment, and the considered signals are ASK-W, ASK-4, BPSK, QPSK, 8PSK, FSK, and QAM.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.5 no.4
• /
• pp.692-698
• /
• 2001

The radio communications by SSB and VHF transceivers are still used very efficiently in coast stations and military base stations. The communication system by the conventional SSB and VHF transceivers between a coast station and a terminal is an one-to-one system. In this dissertation, however, the conventional one-to-one system is expanded to one-to-multiple systems. Then, frequencies can be used effectively for distress, urgency, safety traffic, and military communications. An ICS has been proposed and added, in this dissertation, to the conventional SSB and VHF communication systems, which can realize one-to- several terminal communications. The line switching system by the ICS is to be remote-controlled by ASK modulated PTT signals and audio signals. An ICS can change a connection between terminal and transceiver through a circuit switching system at any time. For this purpose, the author has researched and developed a ASK transmission system, ICS system, control algorithm, multiprocessor system, and moni-toring system. As a conclusion, the developed line switching control systems and equipments can be used effectively for maritime communication, military communication, fishery communication, etc.

• KSBB Journal
• /
• v.13 no.5
• /
• pp.524-529
• /
• 1998

An agarase was partially purified from the culture broth of marine bacterium Bacillus cereus ASK202. Optimal pH and temperature of this agarase were found to be 7.0 and 40$^{\circ}C$, respectively. The maximum productivity of agarooligosaccharides was obtained from 0.3 %(w/v) agar by using of 1 unit agarase. As the results of TLC and HPLC analysis, these oilgosaccharides consisted of neoagarobiose, neoagarotetraose and neoagarohexaose. Under the optimal reaction conditions, 77.5 %(w/v) neoagarobiose and 6.2 %(w/v) neoagarotetraose were produced from agar and the conversion yield of total agarooligosaccharides was 83.7 %(w/v) after for 2 h reaction at 40$^{\circ}C$.

• The Korean Journal of Financial Studies
• /
• v.2 no.1
• /
• pp.127-144
• /
• 1995

Previous literature in financial economics documents the existence of a liquidity premium in expected returns, measured by the bid-ask spread. This study provides a more comprehensive test of the egect of liquidity on common stock returns by including trading volume as an additional liquidity measure. we find that trading volume is a relevant measure of liquidity, and affects expected returns even aher controlling for the effects of systematic risk, firm size, and the relative bid-ask spread. We also find that trading volume complements the bid-ask spread as a liquidity measure, and provides additional information about the liquidity premium. The liquidity effect emerges in non-January months as a volume effect, in addition to the spread effect in January documented by Eleswarapu and Reinganum(1993).

• Proceedings of the IEEK Conference
• /
• 2008.06a
• /
• pp.443-444
• /
• 2008

A double-balanced frequency up-converter using the Gilbert cell structure has been designed with the TSMC $0.18\;{\mu}m$ CMOS library. The frequency up-converter consists of a Mixer core and IF / LO balun. Frequency Up-converter exhibits a 3.4 dB conversion gain with a - 7.6 dBm $P_{1dB}$ for IF power of -10 dBm and LO power of 0 dBm inputs. It also exhibits 92.2 % modulation depth as a ASK modulator.

• Journal of the Institute of Convergence Signal Processing
• /
• v.12 no.1
• /
• pp.44-49
• /
• 2011

The need of data transmission in oceans and other underwater mediums are increasing day by day, so as the research. The underwater medium is very different from that of air. Propagation of electromagnetic wave in water or underground is very difficult because of the conductivity of the propagation materials. In this case, we usually use acoustic signals as ultrasonic but, they are not easy to transfer long distance with coherent method because of time varying multipaths, Doppler effects and attenuations. So, we use non-coherent methods such as FSK or ASK to communicate between long distances. But, as the propagation speed of acoustic wave is very slow, BW of the channel is narrow. It is very hard to guaranty the enough speed for the transmission of digital image data. In previous studies, we proposed this data communication protocol theoretically. In this paper, an underwater channel is modeled and this protocol is tested in this channel condition. The results show that the protocol is 4-6 times faster than ASK. Some relations and results are shown depending on the data length, channel length, bit rate etc.

• Transactions on Electrical and Electronic Materials
• /
• v.11 no.1
• /
• pp.20-23
• /
• 2010

The analog front end (AFE) of a radio frequency identification transponder using the ISO 14443 type A standard with a 100% amplitude shift keying (ASK) modulation is proposed in this paper and verified by circuit simulations and measurements. This AFE circuit, using a 13.56 MHz carrier frequency, consists of a rectifier, a modulator, a demodulator, a regulator, a power on reset, and a dynamically enabled digital phase locked loop (DPLL). The DPLL, with a charge pump enable circuit, was used to recover the clock of a 100% modulated ASK signal during the pause period. A high voltage lateral double diffused metal-oxide semiconductor transistor was used to protect the rectifier and the clock recovery circuit from high voltages. The proposed AFE was fabricated using the $0.18\;{\mu}m$ standard CMOS process, with an AFE core size of $350\;{\mu}m\;{\times}\;230\;{\mu}m$. The measurement results show that the DPLL, using a demodulator output signal, generates a constant 1.695 MHz clock during the pause period of the 100% ASK signal.

• Proceedings of the IEEK Conference
• /
• 1998.06a
• /
• pp.94-97
• /
• 1998

In this paper we derive the pdf for the envelope of the received signal in Nakagami fading environment. Then, using this pdf we analyze the performance of Noncoherent FSK and DPSK in Nakagami fading channel. For ASK it is difficult to find the threshold value in Nakagami fading we confine our discussion in the special case of m=1, which is in Rayleigh fading.